1. Field of the Invention
The present invention relates to a communication device connected to a network and a method of responding to a connection request made to the communication device.
2. Description of the Related Art
Recently, it has become possible to connect devices such as a digital television, a hard disk recorder, and a personal computer to a network and to operate the respective devices in interaction with each other. Examples of such a network include a wireless LAN and a wired LAN. Specifications for exchanging data over a LAN include a protocol specified by the DLNA (Digital Living Network Alliance).
Meanwhile, a technique for realizing communication on an IP network based on a virtual communication channel (session) established between communication devices is becoming prevalent (for example, Japanese Patent Laid-Open No. 2005-33528). Session control protocols for establishing, maintaining and terminating such sessions between communication devices include a protocol referred to as SIP (Session Initiation Protocol; RFC3261). Specifications of SIP are disclosed by the IETF (Internet Engineering Task Force).
However, when executing a service existing on a different network, even if networks are interconnected, such a service cannot be received in a state where a desired service provider has not been initiated.
For example, there is a service performed based on session establishment between a digital television having a DMP function as stipulated by the DLNA and a storage server having a DMS function as stipulated by the DLNA. DMP stands for Digital Media Player and is a client that reproduces contents. In addition, DMS stands for Digital Media Server and is a server that provides contents.
In this example, if a service provider of the storage server is not running, the digital television is unable to receive the service from the storage server.
Furthermore, while other devices can be called up using SIP, devices that can be called up are limited to those supporting SIP.
Moreover, there are cases where a command for causing the service provider to assume a state in which data can be provided is unknown.